As a sensor for use in analysis of an organic molecule, there has been proposed a sensor utilizing a phenomenon where reflected light of a particular wavelength is attenuated in intensity by a local plasmon resonance. It is said that though being simple in structure and less expensive and smaller in structural limitation, the local plasmon sensor is not excellent in detecting sensitivity and it is difficult to carry out a precision analysis by the use of the local plasmon sensor. Since the detecting sensitivity is influenced by the in-plane uniformity of recessed/projected structure (sometimes referred to as “an irregularity”) of the metal fine structure in the sensor surface, there has been proposed a method in which the recessed/projected structure of the metal fine structure is precisely controlled to produce a metal fine structure which is high in the regularity of the recessed/projected structure. See, for instance, Japanese Unexamined Patent Publication Nos. 2004-279364 and 2004-232027.